Technical Field
The present invention relates to a robot provided with a movable unit and a method for designing a shape of a robot.
Related Art
There is a possibility that a robot may collide with a person or a structure in the vicinity when, for example, a movable unit, such as an arm, moves or rotates. Therefore, safety measures are taken. For example, the robot may be surrounded by a safety gate to prevent people from entering the range of movement of the movable unit during operation. However, a situation in which a person enters the range of movement during a setup operation, production, or the like can also be conceived as a possibility. Therefore, safety measures that prevent effects on the human body are also implemented on the robot side. For example, JP-A-2013-193137 discloses providing a detection function for detecting the approach of a human body. The operation of the robot is stopped before the movable unit comes into contact with the human body. In addition, for example, JP-A-2012-110971 discloses providing a mechanism for reducing impact when a collision with the arm is detected.
However, in a configuration in which control is performed to prevent a collision, such as that in JP-A-2013-193137, for example, correct control of the robot, that is, the robot being operated in a normal state is a premise and a requisite. Should an abnormality occur in the robot, the collision prevention control itself cannot be performed. In this way, actualizing intrinsic safety in a robot is difficult in robots configured on the basis of the concept of so-called functional safety.
Furthermore, in a configuration in which a collision prevention mechanism is provided, such as that in JP-A-2012-110971, for example, the collision prevention mechanism starts operation after a collision has occurred. Therefore, the human body is impacted at the instant of collision, and effects on the human body are not necessarily eliminated. In addition, because the weight of the arm increases when the collision prevention mechanism is provided, the output of a driving unit for driving the arm is required to be increased. As a result, the force applied at the time of collision increases, thereby causing concern that the effects on the human body upon collision are actually increased. Moreover, when the output of the driving unit is increased, the driving unit itself becomes larger in size, resulting in a larger robot.
Impact at the time of collision can be reduced by the movable unit being covered with a shock-absorbing cushion material or the like. However, such a configuration leads to situations that are undesirable in terms of the robot. For example, the outer shape of the movable unit (such as an arm) increases in size, resulting in a smaller workspace. The robot may also become larger, as described above.